This invention relates in general to an internal combustion engine in which an air-fuel mixture mixed with a relatively large amount of the exhaust gases is ignited with two spark plugs in a combustion chamber, and more particularly to a cylinder head configuration of the same engine.
In order to suppress the generation of nitrogen oxide (NOx) during combustion of the air-fuel mixture in the combustion chambers of automotive internal combustion engines, it has already been proposed that two spark plugs are disposed spaced apart in the combustion chamber to ignite and combust an air-fuel mixture mixed with a considerably large amount of the exhaust gases fed into the combustion chamber. In general, as the amount of the exhaust gas feed increases, the combustion time is prolonged and accordingly the engine running becomes unstable. However, by the effect of the above-mentioned two spark plug ignition, the combustion time of the mixture in the combustion chamber is shortened, causing stable and smooth running of the engine.
Furthermore, the thus arranged engine is required to improve and stabilize the combustion in the combustion chamber in order to improve fuel consumption characteristics and engine output performance characteristics in addition to reducing noxious gas emission.